I the 43 the Ita fleet included some very good ship, like the Roma, a very good one, almost of the class of the King George V, or (well, almost) Bismark, or similar high profile BBs, and this was one of the reasons that pushed the Germans to try to sink it before the surrender, spoiling the secret weapon FritzX.
For a long time in the war the Ita fleet was stronger than Uk Med Fleet, but Taranto was a major kick in the balls.
There were a couple of battles, later, the problem was'nt the fleet in itself, but the fear that Supermarina (head navy command) had to lose more ships, with the lack of primary resources, could have been really difficult to build new ones, not counting the blow to the interior front (propaganda and regime credibility).
More, there was an inferiority in modern apparatus, like radars (UK navy had 1 heavy cruiser and a BB with range and exploring radar), so during the night the Admiral Campioni felt to be with pants down, with the UK Navy dangerously near to the back

as the loss of an entire cruiser squad showed (Pola and others).
The sorties of Ita Navy BB groups become more rare as the war was proceeding, untill the final surrender.
Another story was the one of the small untis, like the submarines, the "Maiali" (man-guided torpedos - Queen Elizabeth), or the MAS (Motoscafi di ASsalto veloci).
But the latter is the bright part of history
